Monoazo chromium complex



Patented Jan. 25, 1949 Umfrso srArEs Pa, assignors to General poration, New York,

A Delaware NmD aw n intQ-itsfmetalcomplexcorn ounds by the monoafter-'enrmepmeess.

In the dyeing of woolen fabrics by one or another of the mordanting processes, such as chrome mordanting, top-chrome, after-chroming and monochrome or metachrome processes which are commonly employed in the fixing of. acid dyes on the fabrics, it is highly desirable that the dyes be such that they do not stain acetate effects in the fibers. Many dyes, particularly azo dyes, have been developed which are suitable for the after-chroming process and some have been produced which are suitable for the monochrome or metachrome mordanting process. However, few give good results in both processes, In the monochrome or metachrome process, the azo dye is metallized and precipitated on the fiber simultaneously by adding to the dye bath a mixture of an alkali metal chromate and an ammonium salt, such as ammonium sulfate. When the dye liquor is boiled, ammonia is gradually evolved and sulfuric acid formed in the dyebath which at once converts the chromate present into the bichromate. This acts on the dyestuff and fixes it on the fiber as the chrome lake. When the chromate mixture is added to the dye bath, no precipitation takes place so that it is pdssible to dye in one bath. However, if the bichromate is added to the dye bath along with the dyestuif, immediate precipitation of the dyestuff generally takes place. Many dyestuffs are precipitated even by the chromate so that this process is necessarilylimited in its application.

Among those dyes which are said to be suitable for the monochrome or metachrome process is the mono azo dye obtained from diazotized i-nitro-z-aminophenol coupled with N-phthaloylamido hydroxynaphthalene. This dye is described in U. S. Patent 1,411,245 and it is said that, when this dye is dyed in the presence of an alkali metal chromate and an ammonium'salt, such as ammonium sulfate, it will furnish on wool olive tints of an excellent fastness to milling. It has been discovered, however, that the olive tints produced by this dye are of an unattractive dull chrome or vmetachroirie .pr oc'essi as wellj. as the MONOAZO onrtolvirifiiicdm lix- 1 Harry W. Grimmel and Lu Application fiov Serial No. 628 58 1 Claim. .(Cl. 26

shade which as a'*'poor-even1ng color, that is, whenv'iewedunder tificiallli'ghti'it has adifierentshad'e'than whe viewe'd 'und 'f-natural light. wiiee-syemg wsei ras s havi-n acetate-efiects; it has further been '-d1scevi ed that" 'this" dye stains the acetate eiTect fibers a very heavy violet color and also that when dyed by the afterchroming process rather than the monochrome process described in the patent, it yields only very HO- OOH when converted in substance or on thefiber by any of the common metallizing processes into its metal complex compounds produces dyeings of outstanding properties. When applied to wool by the monochrome process, that is, by fixing the unmetallized dye on the wool in the presence of an alkali metal chromateand an ammonium salt,

such as ammonium sulfate, this new dye produces a bright green shade of excellent qualifications.

It is extremely fast to light, crocking and fulling.

It dyes level and ispossessed of a very good evening color. In addition, when dyed as an afterchrome color, the resulting dye is a very powerful greenish-black which leaves acetate fibers unstained.

In order to illustrate how the new dye of this invention may be manufactured without, however,

limiting the invention to this particular method, the following example is given, the parts being by weight unless otherwise specified.

, Earample 10 grams acid is diazotized in the usual way at 0 C. and combined with a solution of 38.3 grams 4-nitro-2-aminophenol-G-sulfonic l-phthaloylamido-7-hydroxynaphthalene 100% M. W. 257 in 200 ml. water, 15 ml. NaOH solution (40% by weight) and 150 cc. of a 20% soda ash solution.

Ice is added to keep the combination tempera ture at 15 C. Test for diazo reaction disappears within one-half hour. By salting out and acidifying to violet reaction on Congo paper, the dye is precipitated. After filtration, the filter cake is pasted with sufllcient soda ash to obtain alkaline reaction. The dye; is then ,-dried by known methods V The dye which is thus obtained dissolves easily in water and yields when dyed on wool by the direct method a black dye which by after-chroming turns to a powerful olive-black. When the dye is dyed on wool accordingto the monochrome process of metachrome mordant process, a bright green shade having excellent fastness to light, cracking and fulling is obtained, which shade does not change to any appreciable extent when viewed under artificial light. "The oliveebla'ck shade obtained by the after-chroming process, when using this dye, also possesses these same good dyeing properties and asindicated above does not stain acetate fiberefiects.

Having now fully described our invention and having illustrated it by aspecific example, clearly setting forth the best manner in which to perform it, what we claim asnew is:- u I We claim: The chromium complex compound obtained by after-chroming of the mono azo dye having the following structural formula:

OH OH HOQS N=N HN do NO:

C O OH HARRY W. GRIMMEL. LUDWIG RICHTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Fleischhauer et a1. Sept. 2. 1941 

